[PATCH 6/8] serial: Add Tegra Combined UART driver

Andy Shevchenko
2018-05-13T14:16:36Z

On Tue, May 8, 2018 at 2:44 PM, Mikko Perttunen <mperttunen@nvidia.com> wrote:
> The Tegra Combined UART (TCU) is a mailbox-based mechanism that allows
> multiplexing multiple "virtual UARTs" into a single hardware serial
> port. The TCU is the primary serial port on Tegra194 devices.
>
> Add a TCU driver utilizing the mailbox framework, as the used mailboxes
> are part of Tegra HSP blocks that are already controlled by the Tegra
> HSP mailbox driver.

First question, can it be done utilizing SERDEV framework?

> +static void tegra_tcu_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
> +{

> + (void)port;
> + (void)mctrl;

Huh?

> +}

> +static void tegra_tcu_uart_stop_tx(struct uart_port *port)
> +{
> + (void)port;
> +}

Ditto.

> + if (written == 3) {
> + value |= 3 << 24;
> + value |= BIT(26);
> + mbox_send_message(tcu->tx, &value);

> + }

(1)

> + }
> +
> + if (written) {
> + value |= written << 24;
> + value |= BIT(26);
> + mbox_send_message(tcu->tx, &value);
> + }

(2)

These are code duplications.

> +static void tegra_tcu_uart_stop_rx(struct uart_port *port)
> +{
> + (void)port;
> +}
> +
> +static void tegra_tcu_uart_break_ctl(struct uart_port *port, int ctl)
> +{
> + (void)port;
> + (void)ctl;
> +}
> +
> +static int tegra_tcu_uart_startup(struct uart_port *port)
> +{
> + (void)port;
> +
> + return 0;
> +}
> +
> +static void tegra_tcu_uart_shutdown(struct uart_port *port)
> +{
> + (void)port;
> +}
> +
> +static void tegra_tcu_uart_set_termios(struct uart_port *port,
> + struct ktermios *new,
> + struct ktermios *old)
> +{
> + (void)port;
> + (void)new;
> + (void)old;
> +}

Remove those unused stub contents.

> + return uart_set_options(&tegra_tcu_uart_port, cons,
> + 115200, 'n', 8, 'n');

Can't it be one line?

> +static void tegra_tcu_receive(struct mbox_client *client, void *msg_p)
> +{
> + struct tty_port *port = &tegra_tcu_uart_port.state->port;

> + uint32_t msg = *(uint32_t *)msg_p;

Redundant casting.

> + unsigned int num_bytes;
> + int i;
> +

> + num_bytes = (msg >> 24) & 0x3;

Two magic numbers.

> + for (i = 0; i < num_bytes; i++)
> + tty_insert_flip_char(port, (msg >> (i*8)) & 0xff, TTY_NORMAL);
> +
> + tty_flip_buffer_push(port);
> +}

> +MODULE_AUTHOR("Mikko Perttunen <mperttunen@nvidia.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("NVIDIA Tegra Combined UART driver");
> diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
> index dce5f9dae121..eaf3c303cba6 100644
> --- a/include/uapi/linux/serial_core.h
> +++ b/include/uapi/linux/serial_core.h
> @@ -281,4 +281,7 @@
> /* MediaTek BTIF */
> #define PORT_MTK_BTIF 117
>
> +/* NVIDIA Tegra Combined UART */
> +#define PORT_TEGRA_TCU 118

Check if there is an unused gap. IIRC we still have one near to 40ish.

--
With Best Regards,
Andy Shevchenko